Inhalation device

ABSTRACT

The present invention relates to a blister pack ( 12 ) having a plurality of blisters ( 13 ) each holding a dose of a powdered medicament comprising a lower base ( 18 ) containing a plurality of cavities ( 19 ) for the powdered medicament and an upper sealing foil layer ( 20 ) which covers the lower base ( 18 ) to form the blisters ( 13 ). Each cavity ( 19 ) is provided with at least one adjacent slit ( 21 ) formed by scoring the foil layer ( 20 ) and a lower base ( 18 ). The slit ( 21 ) ensuring accurate penetration of a cavity ( 19 ) by a suction tube through which a user can inhale the contents of the cavity ( 19 ).

[0001] The present invention relates to an inhalation device, inparticular, an inhalation device for administering a powdered medicamentby inhalation from a blister pack.

[0002] It is known in the treatment of respiratory conditions to makeuse of dry powder inhalers comprising a suction tube arranged so that itis able to cooperate with a blister pack containing a plurality ofindividual blisters each holding a dose of powdered medicament.

[0003] Reference should now be made to WO 97/40876 which discloses aninhalation device comprising a suction tube and a blister pack assembly.The blister pack assembly is in the form of a carrier which holds theblister pack. The carrier is configured such that the upper surface hasa plurality of holes which sit above the blisters in the blister packthereby enabling the distal end of the suction tube to penetrate theblisters as and when required.

[0004] The object of the present invention is to provide an improvedinhalation device of this kind which has a superior construction and ismore user-friendly . In particular, the construction should be light andcompact whilst retaining sufficient rigidity and strength bearing inmind that the user may have to administer the powdered medicament atfrequent intervals. Moreover, the construction should be such that theuser cannot misuse the inhalation device since incorrect delivery of thepowdered medicament could be potentially harmful to the user.

[0005] According to the present invention, there is provided a blisterpack having a plurality of blisters each holding a dose of a powderedmedicament comprising a lower base containing a plurality of cavitiesfor the powdered medicament and an upper sealing foil layer which coversthe lower base to form the blisters , wherein each cavity is providedwith at least one adjacent slit formed by scoring the foil layer andlower base, the slit ensuring accurate penetration of a cavity by asuction tube through which a user can inhale the contents of the cavity.

[0006] Preferably, the opposed edges of a slit are folded back towardsthe lower base to facilitate penetration by the suction tube.

[0007] Preferably, a scored slit sits at a distance of approximately 2mm from the cavity perimeter.

[0008] In a further aspect, the present invention also provides ablister pack assembly comprising the blister pack and a carrier for theblister pack.

[0009] Preferably, the carrier comprises an upper tray and a lower traywhich are interconnectable around the blister pack, the upper tray beingprovided with a plurality of holes and slots which sit above andcorrespond with the positions of the cavities and slits in the blisterpack.

[0010] Preferably, the lower tray is provided with a plurality of slotswhich sit below and correspond with the slits in the blister pack.

[0011] In yet a further aspect, the present invention provides aninhalation device comprising the blister pack assembly and a suctiontube which is constructed for cooperation with the blister pack assemblyhaving a distal end which can penetrate the foil above a cavity, aproximal end through which the user inhales and at least one guide armwhich accurately locates the distal end of the suction tube in a cavityby penetrating the blister pack assembly.

[0012] Preferably, the guide arm or arms have a tapered configuration tofacilitate location in the blister pack assembly.

[0013] Preferably, the suction tube is removably hinged to the carrierby way of cooperating elements on the guide arm or arms and the carrier.

[0014] Preferably, the guide arm or arms are provided with a shallowchannel which facilitates relocation of the suction tube on the hinge.

[0015] Preferably, the distal end of the suction tube is constructed toensure there is an air gap between the suction tube and the blister packassembly when the suction tube penetrates a blister.

[0016] A preferred embodiment of the present invention will now bedescribed, by way of example only, with reference to the accompanyingdrawings, of which:

[0017]FIG. 1 is a perspective view of a preferred embodiment of theinhalation device when enclosed in an outer case;

[0018]FIG. 2 is a perspective view of the inhalation device in FIG. 1when the outer case has been opened;

[0019]FIG. 3 is a perspective view of the inhalation device in FIG. 2showing how the suction tube and blister pack assembly are inserted intothe outer case;

[0020]FIG. 4 is a perspective view of the inhalation device when removedfrom the outer case;

[0021]FIG. 5 is an exploded view of the elements of the inhalationdevice in FIG. 4;

[0022]FIG. 6 is an exploded view of the elements attached to the uppertray of the blister pack assembly;

[0023]FIG. 7 is a plan view of the blister pack in FIG. 5;

[0024]FIG. 8 is a sectional view in direction X-X of the blister pack inFIG. 7;

[0025]FIG. 9 shows the detail of a single blister and slit in plan view;

[0026]FIG. 10 is a sectional view through the blister and slit in FIG. 9(with a modified slit);

[0027]FIG. 11 is a view of one side of the body of the suction tube;

[0028]FIG. 12 is a sectional view in direction X-X in FIG. 11;

[0029]FIG. 13 is a view of the body of the suction tube in direction Ain FIG. 11;

[0030]FIG. 14 is a sectional view in direction X-X in FIG. 13;

[0031]FIG. 15 is a view from above of the proximal end of the body ofthe suction tube in FIG. 11;

[0032]FIG. 16 is a view from below of the distal end of the body of thesuction tube in FIG. 11;

[0033]FIG. 17 is a perspective view of the external sleeve of thesuction tube and resilient strip;

[0034]FIG. 18 is a view from one side of the external sleeve andresilient strip in FIG. 17;

[0035]FIG. 19 is a view in direction A in FIG. 18;

[0036]FIG. 20a shows detail of the guide arm of the suction tube in FIG.18;

[0037]FIGS. 20b and 20 c depict an alternative configuration for theguide arm shown in FIG. 20a;

[0038]FIG. 21 is a sectional view in direction X-X in FIG. 18;

[0039]FIG. 22 shows detail of the connection of the resilient strip tothe external sleeve of the suction tube;

[0040]FIG. 23 is a sectional view in direction X-X in FIG. 21;

[0041]FIG. 24 is a plan view of the upper tray of the carrier;

[0042]FIG. 25 is a sectional view in direction X-X in FIG. 24;

[0043]FIG. 26 is a view in direction A in FIG. 24;

[0044]FIG. 27 is a plan view of the lower tray of the carrier;

[0045]FIG. 28 is a sectional view in direction X-X in FIG. 27;

[0046]FIG. 29 is a sectional view in direction Y-Y in FIG. 27;

[0047]FIG. 30 is a sectional view in direction Z-Z in FIG. 27;

[0048] FIGS. 31 to 37 are various views of the inhalation device whenthe suction tube has been inserted into a blister in the blister packassembly;

[0049]FIGS. 38 and 39 depict detail of the hook on the resilient strip;

[0050]FIG. 40 is an enlarged view of the blister pack assembly;

[0051]FIG. 41 is an enlarged view of an alternative blister packassembly; and

[0052]FIG. 42 is a plan view of the blister pack in FIG. 41.

[0053] Reference should now be made to FIGS. 1, 2 and 3 which arevarious perspective views of a first preferred embodiment of theinhalation device 1 when enclosed in an outer case 2. The outer case 2is hinged having a typical push-button locking mechanism 3. FIG. 4depicts the inhalation device 1 when removed from the outer case 2. Theouter case 2 is constructed such that the inhalation device 1 can slideinto the base 11. The sides of the blister pack assembly 5 cooperatewith the internal surface of the sides of the base 11 to ensure that theinhalation device 1 is held securely in the outer case 2. In addition,the base 11 has two latching elements 50 which cooperate with holes 51in the lower tray 16 (see FIG. 27) which further secure the inhalationdevice 1 in the outer case 2.

[0054] The inhalation device 1 comprises a suction tube 4 and a blisterpack assembly 5. The suction tube 4 is removably connected to theblister pack assembly 5 by an elongate resilient strip 6 which biasesthe suction tube 4 away from the blister pack assembly 5. The resilientstrip 6 is constructed such that when the outer case 2 is closed thesuction tube 4 can lie substantially flat against the blister packassembly 5. On opening the outer case 2, the resilient strip 6 willraise the suction tube 4 such that it can be easily grasped by a user.

[0055] The suction tube 4 is hinged on the blister pack assembly 5. Theinternal surface of the lid 9 of the outer case 2 can optionally beprovided with arms 10 which interlock in a snap-action with the proximalend 8 of the suction tube 4 when the outer case 2 is closed. On openingthe outer case 2, the arms 10 will cooperate with the resilient strip 6to raise the suction tube 4. The arms 10 are constructed to slip overthe proximal end 8 of the suction tube 4 as the lid 9 is rotated awayfrom the blister pack assembly 5 and eventually release the proximal end8, at which point the resilient strip 6 continues to maintain thesuction tube 4 in the raised position.

[0056] In FIG. 3, it is clear how the inhalation device 1 can slide intothe base 11 of the outer case 2. The suction tube 4 and blister packassembly 5 can be removed and replaced when the user has emptied all theblisters 13 in the blister pack 12 seen in the exploded view in FIG. 5.

[0057] The blister pack assembly 5 comprises a carrier 14 and theblister pack 12. The carrier 14 has an upper tray 15 and a lower tray 16which interlock and enclose the blister pack 12.

[0058] In FIG. 6, the elements attached to the upper tray 15 have beenexploded. Suction tube 4 comprises a body 4 a and an external sleeve 4b. However, the suction tube 4 can be moulded as a single part ratherthan as two separate elements. The body 4 a includes the proximal end 8which forms the mouthpiece of the suction tube 4. The external sleeve 4b includes the distal end 7 and comprises guide arms 17 which hinge thesuction tube 4 to the upper tray 15 and facilitate location of thesuction tube 4 in the blister pack assembly 5.

[0059]FIG. 7 is a plan view of the blister pack 12. The blister pack 12has a plurality of blisters 13 arranged in four parallel rows. Eachblister 13 holds a dose of powdered medicament (visible in FIGS. 8 and10). The blister pack 12 comprises a lower base 18 containing aplurality of cavities 19 and an upper foil layer 20 which is sealed tothe lower base 18. There is an optimum minimum sealing distance around ablister 13 in order to ensure that there will be no or very littleingress of moisture within a cavity 19 which could contaminate ordegrade the powdered medicament. The sealing distance “d” from the edgeof a cavity 19 to the edge of an adjacent cavity 19 or a cut edge of theblister pack 12 must typically be at least 2 mm. With this minimumsealing distance in mind, the aim is to reduce the overall size of theblister pack 12 for a given number of blisters 13. However, the blisterpack 12 must also allow penetration of the guide arms 17 of the suctiontube 4 on each side of a blister 13 and, therefore, the foil layer 20and lower base 18 must be cut during manufacture of the blister pack 12.Although the blister pack 12 could be cut by removing appropriatelyshaped slots from the blister pack 12, there is the complication ofremoval of the cut portions of foil and base material. Any cut portionswhich are not removed could fall into a cavity, sit above a blister oraffect the sealing of the foil to the base material. Furthermore, if aslot is cut away from the foil and base material the overall size of theblister pack 12 would have to increase bearing in mind the minimumsealing distance “d” of 2 mm and any additional width of the slot.

[0060] Accordingly, the blister pack 12 is provided with slits 21 whichare simply formed by scoring both the foil layer 20 and lower base 18.In this way, the minimum sealing distance “d” of 2 mm can be achievedwithout adding to the overall size of the blister pack 12.

[0061] Although the guide arms 17 are constructed such that penetrationof the slits 21 requires little force by the user, insertion can befacilitated by folding the opposed edges of the scored foil and basematerial downwardly to increase the width of the slit 21 withoutaffecting the minimum sealing distance “d”. The optional folding of theopposed edges of the slit 21 can be seen in FIG. 10 and FIG. 41.Alternatively, the guide arms 17 can be constructed such that they havea narrower profile than the slit 21.

[0062] The detailed construction of the suction tube 4 will now bedescribed with reference to FIGS. 11 to 23. In FIG. 11 the body 4 a ofthe suction tube is depicted. The body 4 a comprises a mouthpiece 8which forms the proximal end of the suction tube and a cutting mechanism22 at the opposite end. A tapered channel 23 runs from the mouthpiece 8to the cutting mechanism 22.

[0063] The cutting mechanism 22 is constructed to penetrate the foillayer 20 above a cavity 19 and allow the user to inhale the powderedmedicament by breathing in through the mouthpiece 8. FIG. 12 is asectional view in direction X-X in FIG. 11 and depicts by-pass holes 24which will allow an additional air flow to the main air flow from withinthe cavity 19. FIGS. 13 and 14 are additional views of the suction tubebody 4 a. The cutting mechanism 22 including a cutting blade 25 andplunger blades 26 on either side of the cutting blade 25. The cuttingblade 25 will actually penetrate the foil layer 20, whilst the plungerblades 26 act to push the cut foil away to create a clear passage forthe powdered medicament and ensure that all the powdered medicament canbe inhaled from the cavity 19.

[0064] Details of the extern-al sleeve 4 b of the suction tube 4 and theresilient strip 6 can be seen in FIGS. 17 to 23.

[0065] The body 4 a slots within the external sleeve 4 b forming thesuction tube 4 (see FIGS. 5 and 6). The resilient strip 6 has a fixedconnection 27 at one end to the distal portion 7 of the suction tube 4and is connectable by a hook 28 to the upper tray 15 at the opposite endto the hinging point of the suction tube 4 on the carrier (see FIGS. 3and 24). The length of the resilient strip 6 is such that when thesuction tube 4 sits on the hinge arms 29 and the hook 28 is located inthe recess 30 in the upper tray 15, the resilient strip 6 will bendupwardly in an arc. This configuration of the resilient strip 6 resultsin the suction tube 4 being raised on the hinge arms 29. However, theresilient strip is sufficiently flexible to allow the suction tube 4 topivot on the hinge into the position where it will lie substantiallyflat against the upper tray 15 when the outer case 2 is closed.

[0066] In FIGS. 18 and 19 further details of the guide arms 17 andresilient strip 6 are visible. The resilient strip 6 has a protrudingspine 31 which gives the resilient strip 6 a shallow “T” shapedcross-section. The protruding spine 31 is on the underside of theresilient strip 6 and serves to ensure that the resilient strip 6 willarc away from the surface of the upper tray 15. The arcing of theresilient strip 6 will result due to shrinkage effects after themoulding of the plastic material from which the strip is made. There isalso a thickened portion 32 adjacent to the fixed connection 27 whichserves to ensure that the resilient strip 6 does not easily twist orobstruct the slots and holes in the upper tray 15 during use.

[0067] Reference should now be made to FIGS. 20 to 23 which show detailsof the guide arms 17 on the external sleeve 4 b of the suction tube 4.

[0068] In FIG. 20a the external surface of a guide arm 17 is depicted.This surface pivots on a hinge arm 29 on the upper tray 15. In thisconfiguration of the inhalation device, the hinge arms 29 are providedwith a stub 33 and the guide arms 17 are each provided with acooperating hole 34. In order to facilitate location of the guide arms17 on the hinge arms 29, each guide arm 17 has a shallow taperingchannel 35 leading from the outer edge of the guide arm 17 to the hole34. The channels 35 help to re-locate the suction tube 4 on the hingearms 29 after each use of the inhalation device. Preferably, the stubs33 are a snap-fit in the holes 34.

[0069] Each guide arm 17 is also provided with two buttons 36 which areconstructed to be a snap-fit in the slots in the upper tray 15 and lowertray 16 (described in detail with reference to FIGS. 31 to 37).

[0070]FIGS. 20b and 20 c depict an alternative configuration for theguide arm 117. Each guide arm still has a hole 134 which will cooperatewith a stub 33 on the hinge arm 29 and there is a shallow taperingchannel 135 to help re-locate the suction tube 4 on the hinge arms 29after use of the inhalation device. However, a flexible leg 136 areplaces the buttons 36 shown in FIG. 20a. The flexible leg 136 a has abutton 136 b which will be a snap-fit in the slots in the upper tray 15and lower tray 16 of the carrier 14. This alternative configurationattempts to overcome the problem of wear of the buttons 36 which canoccur when the guide arms are constructed of certain materials, inparticular, those which are not flexible enough. Wear of the buttons 36will reduce the snap-fit action and result in less stability when thesuction tube 4 sits in the blister pack assembly 5 during penetration ofa blister. The flexible leg 136 a overcomes this problem because theresilient force can be adjusted. This increase in flexibility also meansthat a larger button 136 b can be used which also improves thesnap-action. It follows that if the material from which the guide arms117 are made is the same as the material from which the hinge arms 29are made, the stubs 33 and holes 134 can also be increased in size toimprove the snap-action of the suction tube 4 when replaced on the hingearms 29.

[0071]FIG. 21 is a sectional view in direction X-X in FIG. 18 of theexternal sleeve 4 b. In this view, by-pass holes 37 can be seen whichalign with the by-pass holes 24 in the suction tube body 4 a. FIG. 23 isa sectional view in direction X-X in FIG. 21 and depicts the internalsurface of a guide arm 17. An enlarged view of the fixed connection 27of the resilient strip 6 to the external sleeve 4 b appears in FIG. 22.

[0072] FIGS. 24 to 26 depict the upper tray 15 of the carrier 14. Inplan view the rows of holes 38 and slots 39 are visible which areconfigured to align with corresponding blisters 13 and slits 21 in theblister pack 12 (see FIG. 7).

[0073] The hook 28 on the resilient strip 6 is intended to be a push-fitinto the recess 30 when the inhalation device is assembled. Thearrow-shape prevents removal of the hook 28 once pushed into the recess30 thereby ensuring that the suction tube 4 remains connected to theblister pack assembly 5. For details of the hook 28 reference should bemade to FIGS. 38 and 39 described later However, the recess 30 willallow a twisting and sideways movement of the hook 28 which is necessaryto ensure that the suction tube 4 can penetrate all the blisters 13without restriction of movement, in particular, when reaching theblisters which lie at the end of the blister pack 12 where the hook 28is held. The twisting movement of hook 28 occurs due to the provision ofa rib 48 (see FIGS. 38 and 39) against which the hook 28 bears, twistingabout the point of contact. On each side of the recess 30 is a lockingslot 40 which cooperates with the push-button locking mechanism 3 on theouter case 2. FIG. 25 is a sectional view in direction X-X in FIG. 24whereas FIG. 26 is a view in direction A in FIG. 24.

[0074] The slots 39 are spaced such that the guide arms 17 on thesuction tube 4 can penetrate easily. However, the buttons 36 on theguide arms 17 are a snap-fit in the slots 39 to ensure that the suctiontube 4 will remain correctly located once a blister 13 has beenpenetrated by the cutting blade 25 and plunger blades 26 (see FIGS. 31to 37).

[0075] Reference should now be made to FIGS. 27 to 30 which depict thelower tray 16. The lower tray 16 is constructed such that it can lockinto position with the upper tray 15 when the blister pack 12 has beeninserted. A plurality of guide pins 41 spaced around the perimeter ofthe upper tray 15 are a snap-fit in corresponding sleeves 42 in thelower tray 16.

[0076] The lower tray 16 is provided with slots 43 which correspond withthe slots 39 in the upper tray 15 and slits 21 in the blister pack 12.The guide arms 17 will enter slots 43 after penetrating the foil layer20 and lower base 18 of the blister pack 12. In FIG. 28 it is clear thatthe slots 43 have a depth provided by a wall 44 around the slotextending from the surface 45 of the lower tray 16. The wall 44 ensuresthat a guide arm 17 will enter the slot 39 in the upper tray 15correctly and that the suction tube 4 remains upright in the carrier 14during inhalation of the powdered medicament by the user. By provisionof the slots 43 in the lower tray 16, the depth of the lower tray 16 canbe less than if the lower tray was solid, in which case, the depth wouldhave to increase by the thickness of the base material of the lower tray16. Clearly, any constructional feature which reduces the size of theinhalation device or the weight makes the device more advantageous anduser-friendly.

[0077] In FIG. 29, which is a sectional view in direction Y-Y in FIG.27, the upright ridges 46 which help to locate the blister pack 12correctly can be seen. However, the ridges 46 also provide support forthe blister pack 12 when the suction tube 4 penetrates a blister 13.Each blister 13 will sit between two ridges 46 thereby ensuring that theblister pack 12 does not slip within the carrier 14 during assembly. Theconnection of the upper tray 15 to the lower tray 16 is achieved byinterlocking pins 41 (visible in FIGS. 24 and 25) and sleeves 42(visible in FIG. 27). In this respect, reference should be made to theblister pack 12 in FIG. 5 which is provided with “U” shaped recesses 47which sit around the interlocking pins 41 and sleeves 42 when theblister pack 12 is assembled between the upper tray 15 and lower tray16.

[0078] The lower tray 16 is also provided with guide pins 49 whichensure accurate location of the blister pack 12 within the lower tray16. During assembly, the blister pack 12 will typically be placed in thelower tray 16 first so that it is important to locate the blister pack12 correctly thereby making the next step of assembling the upper tray15 on the lower tray 16 relatively trouble-free.

[0079] In a preferred embodiment, the guide pins 49 could have a hookedconfiguration to hold the blister pack 12 as well as provide a means forits accurate location.

[0080]FIG. 30 is a sectional view in direction Z-Z in FIG. 27, showingdetails of the slots 43 and ridges 46.

[0081] FIGS. 31 to 37 depict the inhalation device in use when thesuction tube 4 has penetrated a blister 13.

[0082]FIG. 31 is a perspective view of the inhalation device when thesuction tube 4 has been inserted in the first blister 13 in the secondrow from the right of the blister pack 12. The resilient strip 6 nowserves the function of ensuring that the suction tube 4 remainsconnected to the blister pack assembly 5. FIG. 32 is a partial plan viewof the upper tray 15 with the suction tube 4 inserted in one of theholes 38 and adjacent slots 39. In the enlarged view in FIG. 33, furtherdetails are visible of the mouthpiece of the suction tube 4 and throughthe suction tube 4 down to the cutting blade 25.

[0083]FIGS. 34, 35 and 36 are different sectional views in directionsA-A, B-B and C-C respectively in FIGS. 32 and 33. The sectional viewsshow clearly how the suction tube 4 penetrates the upper tray 15, theblister pack 12 and the lower tray 16. FIG. 37 depicts the air flow intothe inhalation device when a user inhales to empty the contents of thecavity 19 and corresponds to FIG. 36.

[0084] In FIGS. 34 and 35, it is clear how the buttons 36 on the guidearms 17 snap into the upper tray 15 and the lower tray 16 to ensure thatthe suction tube 4 remains correctly located during inhalation throughthe mouthpiece by a user. After inhalation the suction tube 4 can beremoved simply by overcoming the slight resistance of the buttons 36when locked in the slots 43.

[0085] It is also important to note that the suction tube 4 isconstructed such that when a blister 13 is penetrated, there is an airgap between the suction tube 4 and the surface of the upper tray 15which allows an air flow A (see FIG. 37). The distal end 7 of thesuction tube 4 which comprises the cutting mechanism 22 is alsoconstructed such that during penetration of a blister 13, there will bean air gap between the cutting mechanism 22 and the perimeter of thehole 38 in the upper tray 15. Furthermore, the blister pack assembly 5is constructed such that there is an air gap between the lower surfaceof the upper tray 15 and the blister pack 12 which allows an air flow B(see FIG. 37). The air flow A and air flow B into the cavity 19facilitate inhalation of the contents by a user.

[0086]FIGS. 38 and 39 show enlarged detail of the arrow-shaped hook 28on the resilient strip 6 when located in the blister pack assembly 5.FIG. 38 is a sectional view which depicts how the hook 28 is held in therecess 30.

[0087] In FIG. 39, which is a view in direction E in FIG. 38, the hook28 is seen to be held just below the upper tray 15. However, asmentioned earlier the hook 28 is able to move within the recess 30 fromside to side and twist as the suction tube 4 moves from blister toblister. The twisting movement is achieved by a rib 48 against which thehook 28 bears, rotating about the point of contact.

[0088]FIG. 40 is an enlarged sectional view through the blister packassembly 5 which shows how the blister pack 12 sits between the uppertray 15 and lower tray 16. The slit 21 has been formed by scoring thefoil layer 20 and lower base 18.

[0089] In FIG. 41, an alternative blister pack 12 is depicted where theslits 21 have been folded or pushed downwards making the slit widerwithout affecting the minimum optimum sealing distance describedearlier. With the folded slits 21, penetration of the blister pack 12 bythe guide arms 17 is made easier. FIG. 42 is a perspective view of justthe blister pack 12 in FIG. 41 depicting the folded slits 21.

1. A blister pack having a plurality of blisters each holding a dose ofa powdered medicament comprising a lower base containing a plurality ofcavities for the powdered medicament and an upper sealing foil layerwhich covers the lower base to form the blisters, wherein each cavity isprovided with at least one adjacent slit formed by scoring the foillayer and lower base, the slit ensuring accurate penetration of a cavityby a suction tube through which a user can inhale the contents of thecavity.
 2. A blister pack as claimed in claim 1, wherein the opposededges of a slit are folded back towards the lower base to facilitatepenetration by the suction tube.
 3. A blister pack as claimed in claim 1or claim 2, wherein a scored slit sits at a distance of approximately 2mm from the cavity perimeter.
 4. A blister pack assembly comprising ablister pack as claimed in any of claims 1 to 3 and a carrier for theblister pack.
 5. A blister pack assembly as claimed in claim 4, whereinthe carrier comprises an upper tray and a lower tray which areinterconnectable around the blister pack, the upper tray being providedwith a plurality of holes and slots which sit above and correspond withthe positions of the cavities and slits in the blister pack.
 6. Ablister pack assembly as claimed in claim 5, wherein the lower tray isprovided with a plurality of slots which sit below and correspond withthe slits in the blister pack.
 7. An inhalation device comprising theblister pack assembly of any of claims 4 to 6 and a suction tube whichis constructed for cooperation with the blister pack assembly having adistal end which can penetrate the foil above a cavity, a proximal endthrough which the user inhales and at least one guide arm whichaccurately locates the distal end of the suction tube in a cavity bypenetrating the blister pack assembly.
 8. An inhalation device asclaimed in claim 7, wherein the guide arm or arms have a taperedconfiguration to facilitate location in the blister pack assembly.
 9. Aninhalation device as claimed in claim 7 or claim 8, wherein the suctiontube is removably hinged to the carrier by way of cooperating elementson the guide arm or arms and the carrier.
 10. An inhalation device asclaimed in claim 9, wherein the guide arm or arms are provided with ashallow channel which facilitates relocation of the suction tube on thehinge.
 11. An inhalation device as claimed in any of claims 7 to 10,wherein the distal end of the suction tube is constructed to ensurethere is an air gap between the suction tube and the blister packassembly when the suction tube penetrates a blister.
 12. A blister packsubstantially as herein described with reference to the accompanyingdrawings.
 13. A blister pack assembly substantially as herein describedwith reference to the accompanying drawings.
 14. An inhalation devicesubstantially as herein described with reference to the accompanyingdrawings.